feat: add GetDashboard and assert every query field carries a uri tag

[NickJosevski]

Closes #442.

GetDashboard

DashboardService implements the non-dynamic endpoint, reusing the existing DashboardQuery and the Dashboard type from #441. Expanded via the service's own URI template, as its siblings do.

Verified against a live server, counts from that instance:

Request	Items	IsFiltered
no parameters	10	false
projectId=<id>	3	true
projectId=<name>	0	true
releaseId=<id>	2	true
selectedTenants=<id>	1	true
selectedTags=Region/Aus-East	1	true
showAll=true	10	false
highestLatestVersionPerProjectAndEnvironment=true	10	false

Filters on IDs only, same as the dynamic endpoint: a name matches nothing and returns an empty dashboard rather than an error. showAll and highestLatestVersion... are accepted but had no observable effect on this dataset, so their behaviour is untested beyond the parameter reaching the server.

DashboardQuery.IncludeLatest

It carried only a url tag. uritemplates reads uri, so it expanded to nothing:

DashboardQuery{ProjectID: "Projects-1", IncludeLatest: true, ShowAll: true}
  -> /api//dashboard?projectId=Projects-1&showAll=true

highestLatestVersionPerProjectAndEnvironment never reached the server. Adds the uri tag with omitempty, which is right because both bools are non-nullable and default to false server side.

Audit test

test/conventions walks every *Query struct under pkg/ and fails on any field without a uri tag, calling out url-only fields specifically. 98 structs across 626 files; IncludeLatest was the only violation. Confirmed it fails when the tag is removed.

It does not catch a uri tag whose name is absent from the template, nor a response type used as a query — which is what #437 was.